1,194 research outputs found
Prediction of metal pm emission in rail tracks for condition monitoring application
No full textExposure to particulate material (PM) is a major health concern in megacities across the world which use trains as a primary public transport. PM emissions caused by railway traffic have hardly been investigated in the past, due to their obviously minor influence on the atmospheric air quality compared to automotive transport. However, the electrical train releases particles mainly originate from wear of rails track, brakes, wheels and carbon contact stripe which are the main causes of cardio-pulmonary and lung cancer. In previous reports most of the researchers have focused on case studies based PM emission investigation. However, the PM emission measured in this way doesn’t show separately the metal PM emission to the environment. In this study a generic PM emission model is developed using rail wheel-track wear model to quantify and characterise the metal emissions. The modelling has based on Archard’s wear model. The prediction models estimated the passenger train of one set emits 6.6mg/km-train at 60m/s speed. The effects of train speed on the PM emission has been also investigated and resulted in when the train speed increase the metal PM emission decrease. Using the model the metal PM emission has been studied for the train line between Leeds and Manchester to show potential emissions produced each day. This PM emission characteristics can be used to monitor the brakes, the wheels and the rail tracks conditions in future
Numerical Analyses of Entropy Production and Thermodynamics Exergy on a Hydrogen-Fueled Micro Combustor Featuring a Diamond-Shaped Bifurcated Inner-Tube Structure for Thermophotovoltaic Applications.
No full textTo improve the heat transfer mechanisms from the thermal energy to the walls, the current work presents a new structure for a micro combustor fueled by hydrogen featuring a diamond-shaped bifurcated inner-tube configuration. For this purpose, a series of three-dimensional (3D) numerical analyses are conducted to investigate the effects of the length of the diamond-shaped structure, width of inner flame channels, inlet equivalence ratio, and hydrogen volume flow rate on the key performance and thermodynamic parameters. In comparison to the conventional design, the outcomes reveal that the proposed configuration exhibits remarkable improvements in energy conversion efficiency, as it reduces the mean exhaust gas temperature by 585.98 K and boosts the exergy and radiation efficiencies by 7.78% and 14.08%, respectively. The parametric study of the design parameters indicates that elongating the diamond-shaped structure and widening the inner flame channels enhance the thermal dynamics and consequently improve the rates of heat absorption by the walls. The increase in the hydrogen volume flow rates feeds the system with additional energy and, therefore, advances the average wall temperature and its uniformity across the external surface. Nevertheless, it also reduces system efficiency due to the limited capacity of the micro combustor to utilize a large energy input along with the high magnitude of entropy production resulting particularly from the mechanism of chemical entropy generation. Operating under a stoichiometric condition balances hydrogen and oxygen in the premixed charge, achieving optimal thermal performance for the micro combustor.This work was supported by the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia [Grant No.: KFU250227]
الفضول المعرفي و علاقتة بالكفاءة الذاتية المدركة لدى طلبة جامعة اليرموك
No full textThe study aimed at uncovering the relationship between epistemic curiosity and perceived selfefficacy, in light some variables. The study sample consisted of (488) students from the students enrolled in the different faculties of the university for the summer semester of the academic year 2016/2017. To achieve the objectives of the study, two measures were used: The future perspective scale (Voskuilen 2010), and the perceived Self-Efficacy measure used by Alwan (2014). The results of the study indicated that the level of curiosity and perceived self-efficacy of the study sample was average. The results showed that there were statistically significant differences in the performance of students on the curiosity scale due to gender in favor males, and regarding specialization in favor of students with scientific specialties, whereas, the level of achievement in favor excellent achievers. Moreover, the result revealed statistically significant differences in the performance of students on the perceived self-efficacy scale due to the gender in favor of males, and regarding the level of achievement, it came in favor of excellent achievers
A New Sensorless Hybrid MPPT Algorithm Based on Fractional Short-Circuit Current Measurement and P&O MPPT
No full textThis paper presents a new maximum power point tracking (MPPT) method for photovoltaic (PV) systems. The proposed method improves the working of the conventional perturb and observe (P&O) method in changing environmental conditions by using the fractional short-circuit current (FSCC) method. It takes the initial operating point of a PV system by using the short-circuit current method and later shifts to the conventional P&O technique. The advantage of having this two-stage algorithm is rapid tracking under changing environmental conditions. In addition, this scheme offers low-power oscillations around MPP and, therefore, more power harvesting compared with the common P&O method. The proposed MPPT decides intelligently about the moment of measuring short-circuit current and is, therefore, an irradiance sensorless scheme. The proposed method is validated with computer software simulation followed by a dSPACE DS1104-based experimental setup. A buck-boost dc-dc converter is used for simulation and experimental confirmation. Furthermore, the reliability of the proposed method is also calculated. The results show that the proposed MPPT technique works satisfactorily under given environmental scenario
The Complexity of Human Walking: A Knee Osteoarthritis Study
No full textThis study proposes a framework for deconstructing complex walking patterns to create a simple principal component space before checking whether the projection to this space is suitable for identifying changes from the normality. We focus on knee osteoarthritis, the most common knee joint disease and the second leading cause of disability. Knee osteoarthritis affects over 250 million people worldwide. The motivation for projecting the highly dimensional movements to a lower dimensional and simpler space is our belief that motor behaviour can be understood by identifying a simplicity via projection to a low principal component space, which may reflect upon the underlying mechanism. To study this, we recruited 180 subjects, 47 of which reported that they had knee osteoarthritis. They were asked to walk several times along a walkway equipped with two force plates that capture their ground reaction forces along 3 axes, namely vertical, anterior-posterior, and medio-lateral, at 1000 Hz. Data when the subject does not clearly strike the force plate were excluded, leaving 1–3 gait cycles per subject. To examine the complexity of human walking, we applied dimensionality reduction via Probabilistic Principal Component Analysis. The first principal component explains 34% of the variance in the data, whereas over 80% of the variance is explained by 8 principal components or more. This proves the complexity of the underlying structure of the ground reaction forces. To examine if our musculoskeletal system generates movements that are distinguishable between normal and pathological subjects in a low dimensional principal component space, we applied a Bayes classifier. For the tested cross-validated, subject-independent experimental protocol, the classification accuracy equals 82.62%. Also, a novel complexity measure is proposed, which can be used as an objective index to facilitate clinical decision making. This measure proves that knee osteoarthritis subjects exhibit more variability in the two-dimensional principal component space
A new irradiance sensorless hybrid MPPT technique for photovoltaic power plants
No full textA hybrid Maximum Power Point Tracking (MPPT) method without using an irradiance sensor is proposed in this paper. The hybrid MPPT method is a combination of conventional Perturb and Observe (P&O) and Fractional Short Circuit Current (FSCC) MPPT technique. The proposed hybrid MPPT decides intelligently about the initial operating point of P&O by using the FSCC MPPT method. This method requires no sensor for irradiation measurement because it detects intelligently about the change in irradiance. Therefore, under dynamic weather conditions the decision about measuring the initial operating point of P&O is intelligent. After finding the initial operating point the system shifts to the conventional P&O method and starts to perturb with a small perturbation size. The use of small perturbation steps enables the system to work with less power oscillations around the Maximum Power Point (MPP), while the use of FSCC helps in rapid tracking of MPP especially under the varying environmental conditions. Thus, the proposed method is fast in tracking the MPP with less power oscillations and hence better performance in terms of energy harvesting when compared with the conventional P&O technique. Impedance matching between solar panel and load is achieved using a DC-DC boost converter and the proposed method is simulated in MATLAB/SIMULINK environment. The system is simulated against the steady and dynamic weather conditions. The results shows that under steady weather condition the proposed method harvests 5% extra energy as compared with the conventional P&O. For dynamic weather conditions the proposed method harness an additional 3.5% energy when compared with the P&O method, which makes it very promisin
The Non-intrusive Detection of Incipient Cavitation in Centrifugal Pumps
No full textThis thesis investigates methods for the detection of incipient cavitation in centrifugal pumps. The thesis begins by describing the working of the centrifugal pump which makes this type of pump particularly prone to cavitation. The basic mechanisms of cavitation are described, which explain why this phenomenon is so damaging.
The thesis reports the results of experiments to predict the onset cavitation using a range of statistical parameters derived from: the vibration signal obtained from an accelerometer on the pump casing, the airborne acoustic signal from a microphone close to the outlet of the pump and the waterborne acoustic signal from a hydrophone in the outlet pipe close to the pump. An assessment of the relative merits of the three methods for the detection of incipient cavitation is given based on a systematic investigation of a range of statistical parameters from time and frequency domain analysis of the signals.
It is shown that is the trends in the features extracted are more than their absolute values in detecting the onset of cavitation. A number of recommendations are made as to which features are most useful, and how future work incorporating these suggestions could give a powerful method for detecting incipient cavitation.
A major contribution of this research programme is the development of a novel capacitive method for the detection of cavitation. Some basic theory is presented to show the principles of the device and then the details of its construction and placement in the test rig built for the purpose. The data for the tests using the capacitive sensor are given and we can say definitely that it has been confirmed as a method of detecting cavitation in a pipe system, and that it is a promising method for the detection of the onset of cavitation
SISTEM INFORMASI PENGKLASIFIKASIAN HASIL BELAJAR PESERTA DIDIK DENGAN TEKNIK DATA MINING METODE K-NEAREST NEIGHBOR (K-NN)
No full textDi sekolah SDN Inpres 046 Sidorejo proses pengklasifikasi hasil belajar atau nilai para Peserta Didik masih secara manual, yaitu menggunakan aplikasi perkantoran yang akhirnya membuat tumpukan data yang sangat banyak. Jadi, selain membuat data excel hasil klasifikasi data semakin bertumpuk juga membuat pengajar kewalahan dalam menentukan hasil penghitungan nilai dan mengevaluasi hasil dari klasifikasi atau nilai akademik peserta didik sehingga boros tenaga, waktu, dan biaya. Penelitian ini bertujuan merancang sebuah sistem informasi klasifikasi hasil belajar pesera didik pada SDN Inpres 046 Sidorejo menggunakan teknik data mining metode K-Nearest Neighbor (K-NN). Untuk memudahkan mengklasifikasi hasil belajar peserta didik di Sekolah Dasar Negeri Inpres 046 sidorejo. Dengan Menggunakan Sistem Informasi Pengklasifikasian Hasil Belajar Peserta Didik Dengan Teknik Data Mining Metode K - Nearest Neighbor (K-NN), maka akan didapatkan hasil belajar pesera didik. Hasil pengklasifikasian nantinya dapat menjadi bahan bagi pihak sekolah untuk melakukan penilaian untuk mendapatkan hasil peserta didik dengan nilai terbaik setiap tahunnya. Penulisan skripsi ini dilakukan pada bulan Februari samapai dengan bulan April 2020 dengan lokasi penelitian pada SDN Inpres 046 Sidorejo Wonomulyo
Sharjah, U.A.E.: the urban conservative dilemma
No full textThis thesis has two broad aims, to outline and analyse the urban development of the city of Sharjah, United Arab Emirates, illuminating significant events leading to the establishment and subsequent spatial expansion of the settlement. This analysis provides the basis from which the second part of the thesis is derived, thus fulfilling the second aim; to create a series of conservation zones in the city based upon the historical, architectural and cultural significance of groups of buildings, plus their feasibility for preservation according to their physical condition. It is to attempt to redress the balance of the wholesale demolition of historic areas of Middle-Eastern cities that this thesis is offered, in the hope that the suggestions contained within may provide, at the very least, a stimulus or springboard that could result in the extension and application of ideas to other Gulf cities, so resulting in the regional development of conservation zones. Chapters 1.1, 1.2 and 2 trace the establishment and development of the settlement called Sharjah, outlining significant historic events and their geographical impact upon the town, including the Master Plan of 1959.Chapter 3 widens the approach, comparing the town to others in the Middle East with respect to components considered to be essential elements of urban cores ('medinas').Chapters 4, 5 and 6 analyse these individual components; religious institutional buildings, suqs and residential structures, collating evidence to create proposed conservation zones based on both broad-based patterns and individual case studies to exemplify such findings in detail. Chapter 7 outlines potential problems of large-scale conservation schemes, offering some possible solutions but significantly, presenting the dilemma common to many such cities: the conflict of land use at the heart of the city: its historic urban core. Chapter 8 concludes the thesis by summarizing all previous evidence and submitting up-to-date findings from a field visit in 1991, thus illustrating any significant developments with respect to conservation in the city
Reexamining the Impact of September 11th on Relations Between Saudi Arabia and the United States
No full textAs a Saudi citizen studying in Boston from 2000-2003, the author received quite an education just being in the United States. With a theoretical framework based on Realism and National Interest, the author examined the impact of September 11th on relations between Saudi Arabia and the United States.
The thesis briefly touches upon the history of Saudi Arabia and traces a chronology of key events in the history of those relations from the PBS series Frontline: Saudi Time Bomb?.
The thesis takes a look at the state of relations between the two nations just prior to September 11th and examines the possibility of an American Grand Plan for reshaping the Middle East.
The author raises such subjects as US attempts to colonize the minds of Middle Easterners, and the West\u27s inability to come to grips with Saudi Arabia not only as the most important oil producer in the region, but as the idealistic Custodians of the two holy mosques of Islam. The author also takes issue with Western attacks against Islam, a religion of peace.
Among other sources, the author relies heavily on interviews of officials involved in Saudi-US relations. In the text the reader will find interviews of Prince Khaled bin Sultan, Deputy Defense Minister of Saudi Arabia; Prince Saud Al-Faisal, Foreign Minister of Saudi Arabia; and Robert W. Jordan, American Ambassador to Saudi Arabia as well as other politicians, journalists and intellectuals in the Kingdom. These interviews shed light on the actual state of relations between the two countries free from hidden agendas and media bias.
The author concludes that despite the war in the media and the war of words in the general populations of the two nations, Saudi-US relations withstood the pressure and challenges that resulted from the terrorist attacks, the nations are cooperating in the war on terror, and relations between the two governments have proven to be strong and enduring
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